Samples of blood and urine contain constituent components that are difficult to analyze directly in minute quantities. When analyzing such components, a sample is generally diluted with a reagent solution, and analysis is performed after the sample and reagent have reacted. However, depending on the sample, the progress of the reaction between the sample and the reagent may be greatly affected by conditions such as temperature, sunlight, humidity and the like, such that there may be wide variation in the results obtained from the same sample depending on conditions.
For example, when analyzing peripheral blood stem cells (PBSC) in the blood, the analysis results obtained may vary greatly if there is a slight change in temperature.
Methods of transplanting stem cells (bone marrow transplants), which are the origin of blood cells, are used as treatments for leukemia. When using methods of transplanting hepatic cells, it is important to accurately know the number of peripheral blood stem cells (PBSC). It is particularly important to accurately know the number of PBSC for peripheral blood stem cell transplantation (PBSCT), which has become widespread in recent years as a method of transplanting hepatic cells.
PBSCT is typically performed as follows. First, the patient is administered a normal dose of chemical agent, which reduces the number of leukocytes in the peripheral blood. The leukocytes begin to increase 5 to 7 days later. It is during this period that the number of PBSC increases in the peripheral blood.
When the number of PBSC in the peripheral blood has sufficiently increased (5 to 20 days), PBSC are collected by a blood component separator, and the PBSC are frozen and stored. When collecting the PBSC, it is important to accurately know the number of PBSC in the peripheral blood. In order to collect an adequate quantity of PBSC for transplantation, PBSC must be collected when the number of PBSC has sufficiently increased.
Then, the patient is subjected to a chemoradiation therapy of proper dosage to destroy the bone marrow. Thereafter, the previously collected PBSC are transplanted into the patient so as to rapidly restore hematopoietic function.
A method of detecting PBSC in peripheral blood has been previously reported (U.S. Pat. No. 5,830,701). The hematopoietic progenitor cells (HPC) described in this publication are collectively cells in the pre-blast differentiation stage among cells differentiating from multipotential stem cells to blood cells of various systems. HPC exist in the peripheral blood and are generically PBSC. Accordingly, HPC and PBSC are identical cells. By this method, it is possible to react blood with a reagent (U.S. Pat. No. 5,413,938) capable of detecting immature cells so as to detect and/or count only HPC without using immunological techniques.
The detection of HPC by this method, however, is subject to wide variation in analysis results when there is even a slight change in temperature.
When sample and reagent are reacted at higher than normal temperatures, conventional analyzers minimize changes in analysis results due to temperature fluctuations by reacting the sample after heating the reagent solution to a predetermined temperature by a heating mechanism.
However, when the environmental temperature is somewhat lower than an ideally suitable reaction temperature, flow path temperature is also lowered. Accordingly, when the reagent solution is supplied from a reagent solution supply mechanism to a detecting mechanism, the temperature of the reagent solution is reduced through contact with the flow path. As a result, the reaction required for analysis does not proceed satisfactorily, thus causing variation in the analysis results for the sample.